The present invention relates to a hybrid compressor system including a hybrid compressor, a drive source of which is switched between an electric motor and an engine for driving a vehicle, for compressing refrigerant.
A hybrid compressor in an air conditioning system for a vehicle is disclosed in Japanese Unexamined Patent Publication No. 2002-67673. An electromagnetic clutch is arranged on a power transmission path between the engine and the hybrid compressor. When a drive source of the hybrid compressor is switched from an electric motor to an engine, the electromagnetic clutch is switched on or connected after a rotational speed of the electric motor becomes equal to a rotational speed of the engine.
Therefore, even when the drive source is switched, the hybrid compressor continuously compresses refrigerant. Namely, air conditioning is continuously conducted by the air conditioning system. Therefore, comfortable cooling feeling can be offered. Furthermore, since the drive source is smoothly switched, unpleasant shock caused by a rotational speed differential between the hybrid compressor and the engine upon switching on the electromagnetic clutch can be avoided.
However, a complicated control, in which the electric clutch is switched on after the rotational speed of the electric motor becomes equal to the rotational speed of the engine, is required. Therefore, a computing load on a control device increases.
The present invention provides a hybrid compressor system that smoothly switches a drive source of a hybrid compressor from an electric motor to an engine without a break of air conditioning and a complicated control.
In accordance with a preferred embodiment of the present invention, a hybrid compressor system has a hybrid compressor for compressing refrigerant, a first drive source, and a second drive source. The first drive source is operatively connected to the compressor through a first power transmission path. The second drive source is operatively connected to the compressor through a second power transmission path. The compressor is selectively driven by one of the first drive source and the second drive source. The hybrid compressor system also includes a first one-way clutch, a driver for driving the second drive source, a sensor for detecting a rotational state of the first drive source and a controller. The first one-way clutch is arranged on the first power transmission path between the compressor and the first drive source for permitting power transmission from the first drive source to the compressor. The controller is electrically connected to the driver and the sensor. When a drive source of the compressor is switched from the second drive source to the first drive source, the controller orders the driver to stop the second drive source after the rotation of the first drive source is detected.
The present invention also provides a method for switching a drive source of a hybrid compressor from a stopped state of an engine for running a vehicle to a normal running state. The compressor is operatively connected to the engine through a power transmission path and selectively driven by one of the engine and an electric motor. A starter motor is operatively connected to the engine. A preferred method includes the steps of providing a one-way clutch on the power transmission path between the compressor and the engine, driving the compressor by the electric motor during an idle stop of the vehicle, detecting a rotational speed of the engine, driving the electric motor such that the electric motor drives the hybrid compressor at a second predetermined speed when the rotational speed of the engine is detected, and stopping the electric motor when the detected rotational speed of the engine exceeds a predetermined value. The predetermined value ranges between a third predetermined rotational speed of the engine that corresponds to a first predetermined rotational speed of the compressor and a fourth rotational speed of the engine that corresponds to the second predetermined rotational speed of the compressor. The compressor is driven at the first predetermined rotational speed when power is transmitted from the starter motor to the compressor through the engine.